This invention relates to ribbon cartridges and, more particularly, to a ribbon cartridge of the type including a supply reel and a take-up reel both rotatably mounted in a common housing in spaced-apart relation.
Ribbon cartridges of the reel-to-reel type in general use today fall into one of two main categories: (1) those where the supply and take-up reels are mounted in the housing at the same vertical level, but are spaced apart horizontally a distance sufficient to enable the full winding of ribbon on the supply reel to be transferred onto the take-up reel; and (2) those where the supply and take-up reels are mounted in the housing at different vertical levels, but with aligned axes of rotation, i.e., they are spaced apart only vertically and not horizontally.
Ribbon cartridges falling into the first category have been most notably used in high speed serial impact printers, such as those employing rotatable print wheels and those of the dot matrix type. One particular high speed serial impact printer which has gained widespread recognition is the HyType I printer manufactured by Diablo Systems, Inc. of Hayward, Calif. The reel-to-reel ribbon cartridges used in that printer, falling into the first category, each have a supply reel and take-up reel which are mounted in the housing at the same vertical level, but in horizontally spaced-apart relation. This relationship has permitted the use of a mechanically simple and inexpensive slip drive mechanism for the take-up reel.
In accordance with such slip drive mechanism, ribbon is removed from the supply reel by a capstan-pinch roller arrangement which feeds the ribbon toward the take-up reel hub. The hub is rotatably mounted about a shaft and has a first pulley integrally formed therewith. The capstan is directly driven by an external drive and has a second pulley integrally formed therewith. A slip ring, such as an O-ring, is stretched about and coupled between the two pulleys. As the capstan is driven to feed ribbon toward the take-up hub, the hub is correspondingly rotated due to the O-ring coupling to take-up the slack and wind it on the hub. As the diameter of wound ribbon on the take-up reel increases, the O-ring is designed to start slipping about the take-up hub pulley, thereby permitting the hub to rotate at the necessary slower rate.
Although these ribbon cartridges have proven quite effective and desirable, particularly in view of the simplistic slip drive mechanism that may be used therewith, it would be desirable to increase the ribbon capacity thereof without substantially increasing the overall dimensions of the housing. At present, the maximum ribbon capacity is limited not only by the dimensions of the housing, but also by the horizontal spacing between the supply and take-up reels, since they are both at the same vertical level in the housing.
Ribbon cartridges falling into the second above-defined category have been most notably used in typewriters. These cartridges are characterized by a guide arm which extends outside of the cartridge housing and guides ribbon from the supply reel mounted at a first vertical level in the housing, over two cooperating 45.degree. angle bends, and then back onto the take-up reel mounted at a second vertical level in the housing. Although the supply reel and the take-up reel are mounted at different levels thereby enabling the maximum wound diameter of each reel to be limited only by the dimensions of the housings, the reels are mounted with their axes of rotation of alignment thereby necessitating the use of a slip drive mechanism much more complicated and costly than the one described above. Further, if these cartridges were used with ribbon having a fast-release ink, there would be a tendency of ink to collect in the vicinity of the two 45.degree. angle bends in the guide arm. An undue amount of collected ink might hamper efficient operation and cause smudging on the printed record medium.
It would be desirable, therefore, to provide a ribbon cartridge having an increased ribbon capacity than those of the first category above described, but which still is capable of using a simplistic slip drive mechanism of the type above described. It would further be desirable if such ribbon cartridge included a guide means for transferring ribbon between the two reels at different levels which did not have any pronounced ink collecting areas, such as the two 45.degree. angle bends of the second category cartridges above described.